/*
 * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
 * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "flutter/sky/engine/platform/transforms/RotateTransformOperation.h"

#include <algorithm>
#include "flutter/sky/engine/platform/animation/AnimationUtilities.h"
#include "flutter/sky/engine/platform/geometry/FloatPoint3D.h"
#include "flutter/sky/engine/wtf/MathExtras.h"

namespace blink {

static const double angleEpsilon = 1e-4;

FloatPoint3D RotateTransformOperation::axis() const {
  return FloatPoint3D(x(), y(), z());
}

bool RotateTransformOperation::shareSameAxis(
    const RotateTransformOperation* from,
    const RotateTransformOperation* to,
    FloatPoint3D* axis,
    double* fromAngle,
    double* toAngle) {
  *axis = FloatPoint3D(0, 0, 1);
  *fromAngle = 0;
  *toAngle = 0;

  if (!from && !to)
    return true;

  bool fromZero = !from || from->axis().isZero();
  bool toZero = !to || to->axis().isZero();

  if (fromZero && toZero)
    return true;

  if (fromZero) {
    *axis = to->axis();
    *toAngle = to->angle();
    return true;
  }

  if (toZero) {
    *axis = from->axis();
    *fromAngle = from->angle();
    return true;
  }

  FloatPoint3D fromAxis = from->axis();
  FloatPoint3D toAxis = to->axis();

  double fromSquared = fromAxis.lengthSquared();
  double toSquared = toAxis.lengthSquared();

  double dot = fromAxis.dot(toAxis);
  double error = std::abs(1 - (dot * dot) / (fromSquared * toSquared));

  if (error > angleEpsilon)
    return false;
  *axis = from->axis();
  *fromAngle = from->angle();
  *toAngle = to->angle();
  return true;
}

PassRefPtr<TransformOperation> RotateTransformOperation::blend(
    const TransformOperation* from,
    double progress,
    bool blendToIdentity) {
  if (from && !from->isSameType(*this))
    return this;

  if (blendToIdentity)
    return RotateTransformOperation::create(
        m_x, m_y, m_z, m_angle - m_angle * progress, m_type);

  const RotateTransformOperation* fromOp =
      static_cast<const RotateTransformOperation*>(from);

  // Optimize for single axis rotation
  if (!fromOp || (fromOp->m_x == 0 && fromOp->m_y == 0 && fromOp->m_z == 1) ||
      (fromOp->m_x == 0 && fromOp->m_y == 1 && fromOp->m_z == 0) ||
      (fromOp->m_x == 1 && fromOp->m_y == 0 && fromOp->m_z == 0)) {
    double fromAngle = fromOp ? fromOp->m_angle : 0;
    return RotateTransformOperation::create(
        fromOp ? fromOp->m_x : m_x, fromOp ? fromOp->m_y : m_y,
        fromOp ? fromOp->m_z : m_z, blink::blend(fromAngle, m_angle, progress),
        m_type);
  }
  double fromAngle;
  double toAngle;
  FloatPoint3D axis;

  if (shareSameAxis(fromOp, this, &axis, &fromAngle, &toAngle))
    return RotateTransformOperation::create(
        axis.x(), axis.y(), axis.z(),
        blink::blend(fromAngle, toAngle, progress), m_type);

  const RotateTransformOperation* toOp = this;

  // Create the 2 rotation matrices
  TransformationMatrix fromT;
  TransformationMatrix toT;
  fromT.rotate3d((fromOp ? fromOp->m_x : 0), (fromOp ? fromOp->m_y : 0),
                 (fromOp ? fromOp->m_z : 1), (fromOp ? fromOp->m_angle : 0));

  toT.rotate3d((toOp ? toOp->m_x : 0), (toOp ? toOp->m_y : 0),
               (toOp ? toOp->m_z : 1), (toOp ? toOp->m_angle : 0));

  // Blend them
  toT.blend(fromT, progress);

  // Extract the result as a quaternion
  TransformationMatrix::DecomposedType decomp;
  toT.decompose(decomp);

  // Convert that to Axis/Angle form
  double x = -decomp.quaternionX;
  double y = -decomp.quaternionY;
  double z = -decomp.quaternionZ;
  double length = std::sqrt(x * x + y * y + z * z);
  double angle = 0;

  if (length > 0.00001) {
    x /= length;
    y /= length;
    z /= length;
    angle = rad2deg(std::acos(decomp.quaternionW) * 2);
  } else {
    x = 0;
    y = 0;
    z = 1;
  }
  return RotateTransformOperation::create(x, y, z, angle, Rotate3D);
}

bool RotateTransformOperation::canBlendWith(
    const TransformOperation& other) const {
  return other.isSameType(*this);
}

}  // namespace blink
